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(No Model.)

J. H. MBHRTENS. FIRE GRATE.

No. 481,237. Patented Aug. 23, I892.

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NITED STATES PATENT OFFICE.

JOHN H. MEHRTENS, OF HARKORTEN, NEAR HASPE, GERMANY, ASSIGNOR TO ERNST JOSEPH KOSTER, OF SAME PLACE.

FIRE-G RATE.

SPECIFICATION fOImiDg' part Of Letters Patent NO. 481,237, dated August 23, 1892.

Application filed January 28, 1892. Serial No. 419,502. (No model.)

In the manufacture of the improved fire- To all whom it may concern.-

Be it known that 1, JOHN H. MEHRTENS, a grate herein described wrought iron or steel citizen of the free city of Bremen, German Emis preferably employed. pire, residing at IIarkorten, near Haspe, in the In the accompanying drawings, Figure 1 is Kingdom of Prussia, German Empire, have an elevation of the grate; Fig. 2, an end view, invented new and useful Improvements in partly in section; Figs. 3 and 4 longitudinal Fire-Grates, of which the following is a speci-' sections through the ends of two of the bars, ficafiolland Fig. 5 a cross-section through the bar.

The object of this invention is the better to The bars d of the grate are hollow and so 10 utilize fuel in heating apparatus by the'emwrought or forged as to have terminal trun- 6 ployment of a grate offering the following adnions fitting suitable hearings in the crossvantages: First, a grate may at any time be pieces act, nuts (1 and keys ebeing preferably readily cleaned, as, owing to its peculiar arused to secure them in position therein; or rangement, no slag can adhere to it, but only the trunnions 0f the bars may be unprovided I 5 solidifies as soon as it comes into contactwith with any screw-threads, the preferable arthe cooled surfaces of the grate; second, hot rangement being to have the two external or air may be conducted under the grate and the outermost bars screw-threaded and fitted into direction of the flames may'be reversed, so nuts and the remaining bars made plain, two that the flame may enter and pass through screw-nuts being sufficient to insure the neo- 20 the spaces between the bars which it could essary tightness and firmness of the whole not be made to do in grates as hitherto used; grate. In cases where the exchange or rethird,thicker layers of fuel may be employed, placement of the bars is known beforehand which enables not only a minimum excess of to be superfluous the terminal trunnions may blast or draft but also inferior qualities of be tapered and driven or wedged into the 25 fuel to be made serviceable; fourth, the steptransverse carriers, whereby of course the like arrangement of the grate renders it exgrate will be rendered still more rigid and ceedingly useful where small coal apt to prosecure. The cooling liquid enters at h and duce much slag has to be employed; and, fifth, fills the hollow space or chamber a up to the the surface of this grate may be comparatively wall or partition 0, from thence through open- 30 smaller than that of other grates, as, owing to ings provided in the trunnions or ends of the the bright flame it enables constantly to be bars, as shown in Figs. 2, 3, and at, it passes kept up, the heating-power is considerablyininto the bars themselves. After thus filling creased. the whole of the hollow cross-piece a it passes Up to the present time fire-gratesarranged through the remaining grate-bars into the 35 for internal cooling where it was important other compartment of a, whereupon it prefto retain the characteristic form of the bars erably issues from the grate at I), though it in section have always been cast, and in conmay be discharged at any convenient point sequence rather wide bars have been proof the sides of the transverse pipe or cham duced and the open spaces between them diberaif more than one partition 0 is provided 40 minished in proportion. The whole of the in it or if no partitions at all are used. In old arrangements, moreover, were somewhat their central parts the bars assume the shape heavy and the bars were only interchangeable in section shown in Fig. 5, while at the ends with difficulty. IVhere wrought-iron was emforming the trunnions they are considerably ployed ordinary cylindrical tubes were geucontracted and present a different shape in 45 erally employed, which shape is altogether section. The wider space situated onalower 5 unsuited for the accomplishment of the essenlevel than the bars of the trunnions in the tial object of the grate, as it necessarily narcenter facilitates the circulation of the coolrows to a considerable extent the open spaces, ing liquid, which is thereby enabled to flow while at the same time offering but an unsatmore rapidly and to be heated to a higher de- 0 isfactory supporting-surface for the fuel. gree than it is in the trunnions and in the transverse pipes. Besides, the wider central space, by enabling a larger quantity of cooling liquid to collect in the main body of each bar, prevents the bars from becoming red-hot too quickly should a momentary interruption occur in the feeding of the liquid. Again, the widened or expanded portion of the grate practically prevents obstruction, the impurities, if any, collecting at the bottom of it. It is exceedingly easy to take the grate to pieces for cleaning or similar purposes.

It will be seen that this grate essentially differs from all existing grates both in object and construction, and in this connection I would particularly point out that the hollow bars are actually formed as gratebars should be and are not wholly or partly cylindrical, for it is well known that cylindrical bars oit'er the most favorable surfaces of adhesion to slag, which, being thus allowed to accumulate, frequently forms big lumps or excrescences in all directions, which seriously interfere with the operation of the furnace and are apt, through the strain they necessitate in stoking and cleaning, to make the bars become loose. Another feature common to all tubular grate-bars hitherto employed is that they have the same innerdiameter or capacity from end to end, the consequence being that very Wide spaces have to be left between them, and when such a bar is disconnected it is scarcely recognizable as a grate-bar at all. The bars of this improved grate, on the contrary, are considerably reduced or contracted at the ends in comparison with their central or main portion.

Hollow grates have before been devised for the circulation of hot water or steam which it was their object to convey directly into the boiler, so that they were really used as apreliminary or feed-Water heating apparatus. The present fire-grate is intended to fulfill no such function, but merely to enable the heating operation to be better carried out, and this result is fully insured by the one circumstance alone that the Water circulating through the grate repels the slag, so that it can neither agglomerate nor adhere to the bars, but splits up into small fragments.

Having now particularly described and ascertained the nature of the said invention and in what manner the same is to be performed, Ideclare that what I claim is A hollow fire'grate adapted to have water circulated through it to prevent the burning on of slag, characterized by the combin ation of hollow grate-bars (1, having reduced perforated ends, with the hollow side bars receiving such ends and with nuts (I for attaching the grate-bars to the side bars, substantially as specified.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

JOHN H. MEHRTENS.

XVitnesses:

WM. EssENwEm, RUDOLPH FRIOKE. 

